Method of separating gases.



H. L. DOHERTY.

METHOD OF SEPARATING GASES.

APPLICATION FlLED MAR-3.19M).

Patented Aug. 17, 1915.

Henry L. DOhErU, SVVUQVLtOi matic plan of my apparatus.

HENRY L. IJOHERTY, OF YORK, N. Y.

METHOD OF SEPARATING GASES.

Specification of Letters Patent.

Patented Aug. 17, 1915.

Application filed March 3, 1910. v Serial No. 547,142.

separating gases with special reference to the separating of thecontaminating constituents of illuminating and heating gases from theuseful constituents.

The object of my invention is to furnish a method of purifying gaseswhich Wlll permit of the use of simple and inexpensive apparatus and ofaccomplishing the punfication with the use of a less volume of scrubbingliquid than is required by present methods.

A further object of my invention is the carrying out of the purificationof gases with liquid instead of solid purifying agents.

As applied to the purification of ord nary coal gas a specific object ofmy lnvention is the carrying out of the purification of the gas in sucha way that a strong ammoniacal liquor may be obtained directly from theseparating chambers Briefly, my invention consists 1n passing the gasfrom which the impurities are to be separated through a series ofchambers, in which the gas is contacted with an absorbent liquid whichflows from chamber to chamber in a direction opposite to the di-'rection of travel of the gas, the contact between the absorbent liquidand the gas being secured by introducing the former into the latter as afog. V The cooling of the gas is effected by passing the fog-laden gasover spiral coils of pipe through WlllCh cooling water is circulated. y

In the drawings, Figure 1 is a diagram- Fig. 2 is a verticalcross-section through one of the separating chambers and a liquidseparator cooperating with the precedinggas chamber on the line'A B ofFig. 3. Fig. 3 is a horizontalcross-section through the same on the lineC D of Fig. 2. Fig. 4 is a section through one'of the spraying caps.

1, 1", 1', etc., are the gas separating vessels.

2, 2", 2, etc., are the vessels in which the gas-absorbing liquid isagain separated from the gas before the latter passes to the nextchamber. 7

- 3, 3, 3", etc., are the pumps for forcing the gas-absorbing liquidfrom one separating chamberto the next.

The gas, which is to ,be treated for the separation of its contaminatingconstituents enters the first separating vessel 1' through the pipe 4and passes successively through all of the sets 12', 1-2", etc. Thesesets of separating vessels are all alike in construction and adescription of the passage of the gaseous current through any one willanswer for all. In the drawings, I have shown in detail the vessels 2"1.In this,

the'mist-laden gas from the vessel 1" enters the vessel 2 from 25". Thispipe 25 is connected with the pipe 26" on the axis of the vessel 2 whichlatter pipe reaches to the bottom of 2". 26" is provided with a largenumber of apertures, 34". The mistladen gas issues through theseapertures along the length of 26 and enters the spiral passage 27 formedby the spiral sheet 28". In passing through 27 a high angular velocityis communicated to the gas current, the liquor particles therein beingthrown to the periphery of the angularly-moving gaseous body and thusinto contact with the outer wall of the passage 27 The force of adhesionbetween the wall surface and the liquor particles is suflicient toretain the fine globules of liquor which coalesce to form the bottom ofvessel 2", from which it is drawn offbyjahe pump 3 and sprayed into thefirst vessel 1 of, the series. The gas, practically freed from thesuspended liquor, discharges from the passage 27 into the collectingchamber 29'. From 29 the gas passes throu h the U-passage 4" into thelower part 0 chamber 1". Here it is again loaded with a spray ofliquor'vwhich is pumped from the vessel 2 by the pump 3", through thepipe 6 to the spray cap 5", by which it is divided into a very finespray. The form of spraying device used may be of. any design which willeffect the thorough atomization of theliquor into a very .fine mist orspray. Preferably it is of' the type of apparatus which I have revealedI and claimed in my Letters Patent No. 901,597, dated Oct. 20th, 1908.It consists of a solid cap, 7, closing a small pressure chamber, 8, intowhich the pipe 6 discharges. This cap 7 is perforated by a plurality ofcouples of fine apertures, 9. The apertures forming each couplea rebored so asto make equal angles in the same plane with the face of thespraying cap 7 at an acute angle with each other. Thefin'e streamsemerging from the cotiperating apertures are thus caused to mutuallyimpinge andinterfere with each other to cause a mutual breaking up ofthe streams to exceedingly fine mist-like globules of liquid, which aretaken up insuspension by the current of. gasentering through the gasinlet pipes 4 of the respective chambers to form a dense fog. In thisway, I secure a more intimate contact between the gas stream and theliquid used than is practicable by any other method, since theimpalpably fine globule of liquid expose to the gas in relation to theweight of the'liquid an enormous surface of contact. It is to be notedthat the fresh water, or whatever other liquid is used, is pumped intothe chamber. 1, the one from which the purified gas discharges, takingup the last of the impurities from the gas, and is separated in thevessel 2. From this, it is pumped by pump 3 into chamber ll, takes upmore impurities from the gas passing through this chamber, is separatedfrom the gas again in 2", andso on, until it is drawn off from 2.through pipe and run or storage well 31. r

In each of the chambers 1, 1" etc., is a set of cooling coils, similarin all respects to the coils 11. of chamber 1". These are simply spiralcoils of pipe, the inner ex-' tremity of the pipe of each coil being'connected to a water supply pipe 12 located at approximately the axis ofthe chamber. The peripheral extremities of the pipes forming the coilsare connected into the through the connection 23 direct to the ofsupplying the'water directly to each of the several coils. in thearrangement shown,

the cooling water-from supply pipe 17 may, if preferred, be introducedfirst intothe' coils of the last gas chamber 1, .through'th'e connection 12?, passes throughthe coils of l,

thence through 13" and l8 ltojthe connec tion 12 to the coils of 1".Fron'i the coils of 1 through the connections 13", 18 12 12-", coilsof1'}, 13", 12' coils of 1', 13', and a 23' to waste main 15. Valves 22,22", 22,

pumped to the separating the liquid films areusually'f'veryconsiderable... The localcirculation of ,th'

pipe 13". From 13 the water may pass l'g bubbles, only th'e particles onthe surraee "of" of securing contact between 22 22*, 22 21',.21 21'", 2121", 21, 20', 20", 20', 20 ",*20Y, 20 control the flow of water throughthe. various-lines. As is obvious from the drawings, by the properadjustment of the valves, a-direct flow of fresh water may beestablished from the water main 17 through there'spective coils of theseparating chambers to the water main 15, as mentioned above. The fog--laden gas passing through these cooling coils has its'temperaturereduced so that the gasabsorbing capacity of the liquid is 'increased.There is, therefore, a still further purification of the gas whilepassing through the liquor separators. As there is more or lessprecipitation of the liquor sprayed into the vessel 1 1, etc., there isa' gradual accumulation of liquor in the bottoms of the v vessels. Tocarry thisofi' overflows 32', 325, 32', 32'", 32 and 32" are provided.These are so arranged that each of the vessels 1, 1", etc., overflowsrespectively into the liquor separator 2", 2", etc., from which the pumpsupplying that particular vessel draws its supply, through theconnecting.

pipes 30, 30", etc., respectively. .Now, in

withdrawing impurities from gases by abof contact necessary between thegas and the liquid and the size of the vessel necessary is simply aquestion of the degree of intimacy of contact that is secured betweenthe liquid and the gas. For the absorption of 'the constituents of thegas which are "soluble in the liquid used, it is essential thateverymolecule of the soluble gases should be brought into substantialcontact with or ex-2 ceedingly close juxtaposition 'wi-th afparti cle ofthe liquid. In ordinary methods ofsecur- 7 ing the contact of the gasand liquidthe former is passed througha chamber in which'in passing itbrushes against amulti tude of thin filmsof liquid. I The interval's.

particles of the gas due to thefformati'onof eddies I is-"relied upon tobringeachg. partic of the gas into'c'ontact with theliqui dfilms topermit of the selective absorptionfby liquid of those particles ofv thegas whieh are soluble in it. Even when the contact be l tween thegasland liquidis'securedflby cau ing the former to bubble throughithelatter,

the gasfpasses through the ,liquidfinwhich are inactual, absorptive:cbfitfict with j the-liquid. Besides, in," is armament 1' I l.S iI q 1ithe hydrostatic head of the latt e overcome by thega s, thus'requiringthe ex}; I penditure of a very considerable amount of s power in themoving of the gas. By my y no method, however, where the gas flows freelthrough the separating chambers the only V resistance opposed to theflow of the gas is simply that due to friction between the gas currentand the walls of the gas passages and cooling coils. The amount of powerrequired is therefore negligible and the gas may be moved with anordinary blower. it is obvious that with theliquid suspended in the gasas a dense fog the interval separating any particle of the gas from aparticle of liquidis indefinitely small. The result is that in any givenchamber, the minute globules of liquid are almost immediately saturatedwith the soluble constituents of the gas under the conditions oftemperature and vapor tension of the several constituents prevailing inthat chamber. As is well known, the solubility of a gas in a liquiddepends in large measure upon the tension of the gas in the atmospherein contact withthe liquid. For this reason, if a sufficient proportionof liquid were supplied to the gas in the one operation to remove all ofthe soluble gases it would be necessary that a very high ratio should beestablished between liquid and gas with a consequent formation of a verydilute liquor. F or this reason it is necessary that the gasbe subjectedto'a number of contacts with the liquid, the direction of flow of liquidand gas being opposite.

In describing my invention I will describe its application to thetreatment of crude illuminating gas to separate therefrom the.

ammonia, carbon dioxid, hydrogen-sulfid, and other impurities. Forthispurpose the liquid used is generally water. The fresh water isintroduced through the spraying device of separating chamber 1. incontact with the gas which has passed through the other chambers andtherefore contains the least proportion of impurities, and passes fromchamber to chamber in the reverse direction to the flow of gas. Thecrude gas enters the separating chamber 1' throu h the pipe 4:,which isconnected with the discharge pipe of blower 10. As it emerges from 4:,the gas is loaded with a dense mist of the absorbing liquid which hasalready absorbed a relatively large proportion of the soluble gases bybeing contacted with gas containing an increasing proportion ofimpurities and which is technically known as ammoniacal liquor. Thefog-laden gas passes upward through chamber 1, the particles of theliquor absorbing soluble impurities of the gas to the saturation pointat the temperature and pressure prevailing in 1. Should the gas asentered through 4 not be fully saturated with water vapor there will ofcourse be an evaporation of the water of the ammoniacal liquor until thegas is saturated. This evaporation would, of course, act to assist inthe cooling of the gas. From 1 the gas passes through 25' to the liquorseparator 2, thence through the U passage 4:" into the chamber 1'.

' From 1 the gas passes through 25", to 2",

through 4' to 1, 25 to 2", 4 to 1 25 to 2 4 to 1", 25 to 2", 4 to 1 25"to 2" and from 2 through the conduit 33 to a storage tank or mains.

When the ordinary illuminating gas is being treated, the ammoniaseparated will carry with it in combination sufficient of the otherimpurities such as carbon dioxid-and hydrogen sulfid to saturate theammonia.

Besides, the liquor will saturate itself with dissolved CO and H 3. Byusing an ammoniacal liquor containing a quantity of free ammonia greaterthan the amount equivalent to the impurities of the gas, substantiallyall of the gaseous impurities may be separated from the gas in theliquor.

An important feature of my invention is the manner in which 1 cool thegases down to a temperature at which the vapor tension of the ammonia islow enough to permit of its separation with substantial completenessfrom the gas. As is well known, the rate of conduction of heat fromWater to water through a separating metal wall is compara- .tively rapidwhile the rate of conduction from. water to gas is relatively quiteslow.

N ow by lading the gas, as I do by my invention, with a dense fog ofwater (in the present case) .1 greatly increase the rate of heat' Itransfer from the gas to waterto a degree,

intact, comparable with the rate of conduction from water to water. Theheat of the gas is almost instantly transferred in part to the suspendedliquid particles. As the gas passes through the coils, a layer of liquidis precipitated upon them which is being constantly swept off by thegaseous current to be replaced byfresh liquid. The eifect is somewhatsimilar to that which is obtained in the cooling coils for ammoniacommonly used in connection with refrigeration works, except that thefluid to be I very dilute nitric oxid gases formed by the.

several electrolytic methods for manufacturing nitric acid fromatmospheric nitrogen, from the diluent gases. Itis also an admirablemethod for the separation'of carbon-dioxid from combustion gases by absorbing the same in alkali solution for the purpose of obtaining pure.carbon-dioxid &

for liquefaction. There are many other cases occurring in the various1ndustr1es m which my invention may be advantageously I applied.

Having described my invention, what I claim is 1. The process ofseparating gases which comprises projecting upward into thetgas mixtureand in the direction of flow of said mixture a fog or mist of anabsorbent liquid, whereby the liquid particles of said mist are causedto be borne in suspension by said gas mixture to absorb solubleconstituents of the same, cooling said mist laden gas mixture,

in a liquid, vertically projecting saidliquid upward in an atomizedcondition into the said gas mixture and 1n the dlrection of flow of saidgas mixture, whereby particles of said atomized liquid of sufficientfineness to be floatant in said gas mixture are borne along the same,while the larger particles of said liquid are caused to fall through thesaid upwardly moving gas mixture in the direction contrary to thedirection of their projection into said gas mixture and their period ofcontact with said gas mixture prolonged, cooling the said gas mixtureWhile laden with said atomized liquid, and removing said atomized liquidfrom said gas mixture by contacting the particles of said liquid withprecipitating surfaces by leadmg said gas mixture through a spiral pathat a comparatively high Velocity.

3. The process of separating easily soluble gases from relativelyinsoluble gases which: comprises, subjecting the gas mixture to aplurality of cooling operations, injecting into the said gas mixturebefore each cooling operation, while the said mixture has a verticallyupward flow and in the direction of said flow, a mist of an absorbentliquid,

prolonging contact between said gas mixture and said mist untilsaturation equ1l1b-' rium has been established while subjecting said gasmixture to cooling, and separating from the gas mixture the mistinjected in one operation before the injection of absorbent liquid inthe next cooling operation.

4. The process of separating soluble gases from relatively insolublegases which com prises injecting into the vertically upward flowing gasmixture and in the direction of flow of said mixture a mist of a solventliquid, passing the mist-laden gas mixture in contact with coolingsurfaces until the :said mist is substantially saturated with thesaidsoluble gases, separating the said mist from the said gases, againestablishing a substantially upward flow of said gas mixture andinjecting into the said mixture in the direction of its flow a secondportion of misted solvent liquid containing a lower proportion of thesoluble gases than the first portion of said liquid, subjecting'themistladen gas mixture to further cooling, where by further quantities ofthe soluble gases are dissolved by said second portion of solventliquid, separating the said second portion of solvent liquid from saidgas mixture, and repeating said operations with further portions ofmisted solvent containing successively a lower and lower proportion ofdissolved gases, and at successively lower temperatures, until thedesired proportion of the soluble gases of said gas mixture have beenseparated therefrom.

5. The process of separting from a gas mixture one or more constituentsthereof 4 which are capable'of absorption in a liquid which-comprisescooling the gas mixture to a temperature at which one or more of thesaid constituents are soluble in said liquid,

introducing thereinto a portion of the absorbent liquid as a mist, theliquid particles formmgsaid mist being of such size as to be floatant insaid gas mixture, prolonging contact between said gas mixture and saidmist until saturation equilibrium has been established between said gasmixture and said liquid, subjecting the gas mixture while laden with themist of absorbent liquid to cooling, separating out the said firstportion of absorbent liquid, introducing into the unabsorbed gases asecond-portion of absorbent liquid as a mist, subjecting'the. said gaseswhile laden with the mist of the said second portion of absorbent liquidto cooling, separating the said mist of the said second portion ofabsorbent liquid from the unabsorbed gases after said SBCOIIdPOItlOH,

of liquid has become saturated with constituents to be removed, andrepeating the said operat ons until the desired proportion of theconstituent which it 'is desired to sepa-' rate from the gas mixture hasbeen absorbed by the said absorbent liquid.

6. Theprocess of separating mixed gases which comprises passing the gasmixture successively through a series of chambers, introducing into thegas mixture in each chamber a mist of an absorbent liquid, the jparticles of liquid forming said mist being of suflicient fineness to befloatant in said gas mixture, prolonging contact between said gasmixture and said mist until saturation equilibrium has beensubstantially established between said gas mixture and said liquid,cooling the" mist-laden gas mixture after the same has passed throughone chamber and separating the mist from the unabsorbed gases of themixture before introducing the same into the next chamber, the saidabsorbent liquid being first introduced into the portion of the gasmixture passing through the last chamber of the series and then into theportion of the gas mixture passing through the other chambers in thereverse order to that of the progression of the gas mixture.

T. The process of separating gases soluble in water from gases which arerelatively insoluble in water, which comprises, subjecting the gasmixture to a number of succes- 'sive cooling operations to effect agraduated cooling of said gas mixture, injecting into the said gasmixture before each cooling operation a plurality of fine streams ofwater at a high velocity, said streams being so directed relatively toeach other as to efiect mutual impingement and disintegration to producea mist whose particles are of such size as to be floatant in the currentof said gases, and removing from the gas mixture the mist injected inone operation before the injection of water in the next operation, thesaid water being successively injected into the said gas mixture in saidcooling operation in the reverse direction of progression to that of thesaid gas mixture.

8. The process of separating gases soluble in water from gases which arerelatively insoluble in water, which comprises, subjecting the gasmixture to a number of successive cooling operations to effect agraduated cooling of said gas mixture, injecting into the said'gasmixture in the general direction of the flow of said mixture, beforeeach cooling operation, a plurality of fine streams of water at a highvelocity, said streams being so directed relatively to each other as toeffect mutual impingement and disintegration to produce a mist whoseparticles are of such size as to be fioatant in the current of saidgases, and removing from the gas mixture the mist injected in oneoperation before the injection of water in the next operation, the saidwater being successively injected into the said gas mixture in saidcooling operation in the reverse direction of progression to that of thesaid gas mixture,

whereby soluble impurities are dissolved in said water and therebyseparated from said gas mixture.

9. The process of separating ammonia and other gases from crude coalgas, which comprises, establishing a pluralityfof contacts between saidcrude gas and an oppositely progressing body of absorbing liquid, thesaid liquid during said contacts being reduced to the fineness of amist, said mist being formed by discharging under pressure into saidcrude gasa plurality of mutually impinging streams of said liquid,whereby said streams are disintegrated to form said mist, and subjectingthe mist-laden gas during each of said contacts to graduate cool ing.

10. The process of separating ammonia and other gases from crude coalgas, which comprises, establishing a plurality of contacts between saidcrude gas and an oppositely progressing body of absorbent liquid, thesaid liquid during said contacts being reduced to the fineness of a mistsaid, mist being formed by discharging under pressure into said crudegas a plurality of mutually impinging streams of said liquid, wherebysaid streams are disintegrated to form said mist, subjecting themist-laden gas during each of said contacts to graduated cooling,separating the mist introduced during one of said contacts from said gasmixture in the liquid cbndition, moving the separated liquid in theopposite direction to that of

